The difficulty of the trip up to Buffalo Boy Mine varies on the season's conditions which affect the state of repair of the road. The year Art and I travelled it, it'd been rather rainy so we found a few washed out places on the shelf road leading up. Generally it's nothing too crazy. Much of the trail is shelf road. I don't recall any significant obstacles.
The most significant part of the trail, of course, is its namesake, a huge tram station, a fairly well-preserved building some 15-20' tall and wide, and at least twice that in length. The station is set almost within throwing distance of the top of the mountain. How many people have been to the top of a mountain? The alpine scenery is breathtaking. Delicate greens cascade down the gentle slopes that form the valley twisting and sloping its way down the mountain. You can see so far here. You watch as huge clouds throw shadows over peaks that appear to be in walking distance. It's as if you're right now in the middle of everything truly important that happens at such a distance when you're back in Denver staring west.
From Silverton, head east on Highway 110 towards Stony Pass, turning right after five miles on County Road 4, a graded dirt road. At the intersection of CR 3 and 4A, bear left along CR 3. You'll soon find another fork where CR 3 heads to the right towards Stony Pass. Instead, bear left up a steep grade. Take the switchbacks to the right, up a steep grade through big trees and then up along an open steep rocky grade. An old shack will be on your left. Just keep following this trail and soon you'll pass a tram tower on the right and you'll see the enormous Buffalo Boy Mine remains. You can go on past this further towards the top of the mountain. You might want to spend some time here exploring but please don't damage anything and don't take souvenirs!
Sources
Guide to Colorado Backroads & 4-Wheel Drive Trails, Charles A. Wells
Buffalo Boy Mine, Miss Molly,
and Troubled Child, photo by Michael Shimniok